[racket-dev] planet versioning spec?

In the planet documentation, I don't see a spec of the semantics of
versioning.  (If it's there, can someone please point me to it?)

My understanding is this; can someone confirm or correct it?  (The
#lang part probably isn't relevant, but since that's how I need to use
it, I'm being maximally specific.)

If I say

  #lang planet foo/bar:1:1

that presumably is an explicit reference to :1:1, no more and no
fewer.  If I just say

  #lang planet foo/bar

I mean "the latest version of foo/bar that I've downloaded; don't go
checking right now for whether there's a newer version".  So if
foo/bar has moved on to :1:2, I'm still running :1:1.  But I say ONCE

  #lang planet foo/bar:1:2

that will download and install it; subsequently,

  #lang planet foo/bar

refers to :1:2.

(I *think* this is part of what the section "Previous Linkage" says --
http://docs.racket-lang.org/planet/search-order.html
-- but not all of this is specified.)

Shriram